Strength material data

Stress-strain diagram comparing the performance of a bulk metal glass with other high strength materials. Data for these plots were taken from Table 9.1. 

In an isotropic material subjected to a uniaxial stress, failure of the latter type is straightforward to predict. The tensile strength of the material will be known from materials data sheets and it is simply a question of ensuring that the applied uniaxial stress does not exceed this. 

For the materials data given in Table 3-1 a GRP panel having 2.4 times the thickness of a steel panel has the same flexural stiffness but 3.6 times its flexural strength and only half its weight. The tensile strength of the GRP panel would be 50% greater than that of the steel panel, but its tensile stiffness is only 17% that of the steel panel. The designer s interest in this GRP panel would then depend in this context on whether tensile stiffness was what was required. 

These formulas are also used to determine the pressure required to produce elastic deformations by using yield strengths for SM. They are also used to determine the pressures required to produce failures by using tensile strengths for SM. Strength of material data are provided in Table 12-3. 

A very important factor that should not be overlooked by a designer, processor, analyst, statistician, etc. is that most conventional and commercial tabulated material data and plots, such as tensile strength, are average or mean values. They would imply a 50% survival rate when the material value below the mean processes unacceptable products. Target is to obtain some level of reliability that will account for material variations and other variations that can occur during the product design to processing the plastics... 

Fatigue data of corrosion resistant steels and other relevant high strength materials are easy available for non-corrosive ambiance (air, oil). For the large variety of liquids applied in production processes the data have to be evaluated from special fatigue tests with corrosion cells. This paper answers the question if such uniaxial test results can be applied for the real component design in order to meet three-axial corrosion fatigue reality well. 

Althongh hydrogen embrittlement is more severe at high gas pressnres and in high-strength steels, strnctnres can still be designed with steels nnder these conditions by using fracture mechanics. Provided material data are available for steels... 

Figure 1. Specific ultimate tensile strength vs. specific stiffness of current and developmental aerospace structural materials. Data are displayed on a log-log plot in (a), where P signifies PAN-based reinforcements Gr represents graphite fibers 0 0 and 90 0 indicate data collected parallel to and transverse to the fiber direction in uniaxial composites, respectively and Q/I represents quasi-isotropic laminates. The (f represents fiber reinforcements in MMCs. The dashed line in (b) represents the combinations of specific strength and stiffness that are double those of conventional metal alloys.

The subject of impact strength of plastics has received considerable attention in official standards, material data sheets and literature at large. 

The tensile creep and tensile strength test data are required for Superpave mixtures to determine the master relaxation modulus curve and fracture parameters. The master relaxation modulus curve controls thermal crack development, while the fracture parameter defines a mixture s resistance to fracture. The tensile creep data may be used to evaluate the relative quality of materials. 

The subscripts T and m in the above formulae relate to the fibres and matrix respectively i.e. on is the strength of the fibres in tension. The characteristic lamina strengths, namely ou, Oic, 02t, 02c and 012, which have been calculated from raw material data, can then be used with Equation (4.56) to check for possible failure of the lamina. 

Figure 7 Dependences of the size exclusion distribution coefficient, K, for the small globular protein hen egg white lysozyme versus the ionic strength, /, of the mobile phase for several notional size exclusion sorbents of different average pore diameter, particle size, and surface chemistry characteristics. The sorbents employed in these investigations were 1, Synchropak GPC 100 2, Waters I-125 3, Shodex OH Pak B-804 4, Lichrosorb Diol 5, Tosoh TSK SW 3000 and 6, Tosoh TSK SW 2000. The Interplay of hydrophobic interaction and electrostatic phenomena, superimposed upon the size exclusion effect due to the differences in the pore sizes of the support materials, is particularly evident with these sorbents at high- and low-ionic-strength conditions. (Data ad ed from Ref. 98.)...

In all ready-mix concrete plants the material data and compositions for a variety of needs are stored and may be used again in various combinations, together with obtained results strength, its development in time, rheological properties, etc. Such databases enable easy design of any kind of concrete in an economic way, with some modifications for actual demand. Also, necessary trial batches should always be executed. 

The material data sheet should show the difference in impact strength between notched and unnotched test bars. In some materials this ratio is 1 to 30, but in others there is also a decided reduction in the strength of the notched bars. Some show no strength reduction, however. In a shaped product an inside sharp comer is an indication that a certain specified tough material acts in a brittle manner. Sharp comers become stress concentrators. 

The data presented at room temperature for tensile strength change provide chemical resistance at average conditions. These data are applicable where the application only requires that the material support itself. For those composites used in engineering applications, the strength change data at 0.25% strain offer more utility. 

The data obtained using the test method reviewed should be reported as direct shear strength. These data can only be compared to data determined by the same direct-shear methods. This test cannot be used to develop shear S-S curves or determine a shear modulus, because bending or compression rather than pure shear transfer a considerable portion of the load. The test results depend on the susceptibility of the material to the sharpness of load faces. 

Because there is a certain randomness to the kind and distribution of surface flaws that are typical for a certain material as well as for its production process, strength measurement data are statistical data and have to be treated in a statistical way. In most cases the strength is adequately described using the Weibull distribution. 

The most frequently used materials data for short-term loading are those for Young s modulus and ultimate strain. Allowances for reductions include for duration of acting load, A2 for media influence incl. weathering, moisture, chemicals, and A3 for temperature. Various factors are selected that correspond with the material data, so that, in addition to reductions in terms of load, strength, stiffness (stability) and deformability (strain limit), distinctions are made for environmental influences and load duration, e. g., Aj for reduction due to load duration until fracture, A,y for stability, and A,u ultimate strength. 

The compiling and evaluation of material data are rightfully the responsibility of the Subcommittee on Properties of Metals. ITie three subgroups involved would be the SG on Quenched and Tempered Steel, the SG Strength-Steel and High Temperature AUoys, and the SG Strength-Nonferrous Alloys. 

A description of the data required for proper preparation of the design charts follows. It is felt that these are minimum requirements for the preparation of reliable charts. The use of so-called typical stress-strain curves based on a statistically significant volume of data may be satisfactory if the region between the proportional limit and the yield strength is accurately represented. The development of the tangent modulus in this region is a critical step. It is suggested that this description be prepared in a form suitable for attachment to any requests for material data from an inquirer. 

Three basic tests have been developed and accepted by the plastics industry. If the application does not require the product to be exposed to elevated temperature for a long period under continuous load, a simple heat-resistance test is adequate. The applications requiring the product to be under continuous significant load must be looked at from creep modulus and creep rupture strength test data. Another widely accepted method of measuring maximum continuous use temperature has been developed by Underwriters Laboratories. The UL temperature index, established for a variety of plastic materials to be used in electrical applications, is the... 

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